Windberger, U., R. Plasenzotti, and T. Voracek (2005). The fluidity of blood in African elephants (Loxodonta africana). Clinical Hemorheology and Microcirculation 33(4): 32
1-6.
Abstract: The large cellular volume of erythrocytes and the increased plasma concentration of proteins in elephants are factors which potentially affect blood rheology adversely. To verify blood rheology, routine hemorheologic variables were
analyzed
in four African elephants (Loxodonta africana), housed in the zoo of Vienna. Whole blood viscosity at three different shear rates (WBV at low shear rate: WBV 0.7 s(-1) and WBV 2.4 s(-1); WBV at high shear rate: WBV 94 s(-1) done by LS30,
Contraves)
and erythrocyte aggregation (aggregation indices AI by LS30; aggregation indices M0, M1 by Myrenne aggregometer) were high (WBV 94 s(-1): 5.368 (5.246/5.648); WBV 2.4 s(-1): 16.291 (15.605/17.629); WBV 0.7 s(-1): 28.28 (25.537/32.173) mPa s; AI 2.4 s
(-1): 0.25 (0.23/0.30); AI 0.7 s(-1): 0.24 (0.23/0.28); M0: 7.8 (6.4/8.4); M1: 30.2 (25/31)). Plasma viscosity (PV) was increased as well (1.865 (1.857/1.912) mPa s) compared to other mammalian species. These parameters would indicate a decrease in blood
fluidity in elephants. However, erythrocyte rigidity (LORCA, Mechatronics) was decreased, which in contrast, has a promotive effect on peripheral perfusion. Blood rheology of the elephants was determined by a high whole blood and plasma viscosity as the
result
of pronounced erythrocyte aggregation and high plasma protein concentration. Thus, in the terminal vessels the resistance to flow will be increased. The large erythrocytes, which might impede blood flow further due to geometrical reasons, however,
had
a pronounced flexibility. We conclude that the effect of the increased inner resistance to peripheral blood flow was counteracted by the decreased rigidity of the erythrocytes to enable an adequate blood flow in African elephants.
Descriptors: blood proteins analysis, blood viscosity physiology, elephant blood, erythrocyte volume physiology, hemorheology methods, horse blood.